Steric hindrance and orientation polarization by a zwitterionic additive to stabilize zinc metal anodes

Abstract

Zinc metal stands out as a promising anode material due to its exceptional theoretical capacity, impressive energy density, and low redox potential. However, challenges such as zinc dendrite growth, anode corrosion, and side reactions in aqueous electrolytes significantly impede the practical application of zinc metal anodes. Herein, 3-(1-pyridinio)-1-propanesulfonate (PPS) is introduced as a zwitterionic additive to achieve long-term and highly reversible Zn plating/stripping. Due to the orientation polarization with the force of electric field, PPS additive with π–π conjugated pyridinio cations and strong coordination ability of sulfonate anion tends to generate a dynamic adsorption layer and build a unique water–poor interface. PPS with steric hindrance effect and strong coordination ability can attract solvated Zn²⁺, thereby promoting the desolvation process. Moreover, by providing a large number of nucleation sites and inducing zinc ion flow, the preferred orientation of the (002) crystal plane can be achieved. Therefore, the interfacial electrochemical reduction kinetics is regulated and uniform zinc deposition is ensured. Owing to these advantages, the Zn//Zn symmetrical cell with PPS additive exhibits remarkable cycling stability exceeding 2340 h (1 mA cm⁻² and 1 mA h cm⁻²). The Zn//V₂O₅ full cell also delivers stable cycling for up to 6000 cycles.